The objective of this research program is to demonstrate the feasibility of a new controlled-release technology for use in an injectable formulation of buprenorphine to improve treatment of opioid dependence. The key to the new technology is the use of bioerodible microporous microbeads with a controllable structure that allows for high drug loadings as well as easily varied release rates and durations of release. These controlled-release microbeads would be used in an injectable formulation that would result in much-improved patient compliance, better efficacy, and fewer side effects than is the case with current therapies. Specific tasks in Phase l include identification of bioerodible polymers, preparation of candidate microporous microbeads, in vitro testing of drug- loaded microbeads, determination of short-term stability. and in vivo evaluation of candidate microbeads in rhesus monkeys. The feasibility of this approach will be demonstrated if the in vitro and in vivo tests indicate efficacy over 3- to 14-day time periods. If this is the case, a Phase Il program will be focused on further development of this technology and completion of preclinical studies necessary for submission of an Investigational New Drug application. PROPOSED COMMERCIAL APPLICATION: Successful development of this technology for injectable formulations of buprenorphine would lead to more effective treatment of opioid dependence. The same technology could also be useful for treatment of chronic pain, treatment of cocaine dependence, and delivery of peptide or oligonucleotide drugs, hormones, and vaccines.